Cutting tool



April 1942- .1.- J. GILLICH 2,279,979

CUTTING TOOL Filed Feb. 2, 19'40 By MM ATTORNEY Patented Apr. 14, 1942CUTTING TOOL James J. Gillich, Elizabeth, N. J., assignor to BellTelephone Laboratories,

Incorporated,

New York, N. Y., a corporation of New York Application February 2, 1940,Serial No. 316,945

2 Claims. ((1125-13) p This invention relates to a cutting tool and moreparticularly to a saw'for cutting Rochelle salt and similar brittle,water soluble, materials.

An object of the invention is to facilitate cutting Rochelle salt andsimilar materials.

A more specific object of the invention'is to,

prevent the accumulation on the edge of the blade of particles of thematerial being cut.

In the preparation of Rochelle salt plates,

which have been utilized for some time as piezoelectric elements inelectrical circuits such as oscillators and filters and which have morerecently been proposed for use in electrical relays, as disclosed, forexample, in Patent 2,166,763, issued July 18, 1939, to W- P. Mason, histhe usual practice to cut a number of relatively thin, substantiallyflat, plates or slabs from a larger crystal.

Various methods and means have been proposed in the past for cuttingthese thin plates including the wet-string cutter, the mud saw and sawsutilizing toothed blades; none of these has, however, in applicantsexperience, been entirely satisfactory. In some instances the operationhas been entirely too slow to be commercially feasible, inothers it hasbeen practically impossible to produce plates of the desired thinnessand with the necessary high degree of plane parallelism, while in stillother instances excessive breakage of the fragile material has resulted.

In the case of the so-called mud saw, which commonly comprises a thindisc of steel or copper rotating in a liquid, such as water, containingabrasive, it is applicants belief that unsatisfactory cutting ofRochelle salt and similar materials has resulted mainly from the factthat a salty accumulation tends to become glazed on the cutting edge ofthe disc thereby slowing down the cutting process to an unsatisfactoryrate. Breakage of the fragile material also has resulted due to coolingof the material caused by evaporation of the liquid.

A feature of the present invention is means whereby the saltyaccumulation which tends to become glazed on the cutting edge of theblade is broken away.

A further feature of the invention is an abrasive carrying liquid whichdoes not tend to cause V cooling of the material being cut due toevaporation.

In accordance with a specific embodiment of comprises abrasive particlescarried in kerosene.

become glazed on the edge of the blade.

Means are provided for supporting the material to be cut in contact withthe cutting edge of the disc. A portion of material substantially harderthan the material being cut, for example if Rochelle salt is being cutthe material may be quartz or glass, is held in cutting engagement withthe edge of the disc. Engagement of the cutting edge of the disc withthis material is effective to break away any accumulation which tends toThe cleaningtmaterial is out very slowly as comthe invention, a metaldisc, for example of steel or copper,is provided which is rotatedcomparatively slowly, for example at a speed of revolutions per minute,in an abrasive liquid which pared to the rate at which the othermaterial is out due to the greater hardness of the firstm'entionedmaterial.

A thorough understanding of the arrangement contemplated by the presentinvention as well as appreciation of the various desirable featuresthereof may be gained from consideration of the following detaileddescription and the accompanying drawing in which the single figure is aview in perspective of a cutting tool which embodies features inaccordance with the present invention.

Referring now to Fig. 1, driving motor II is shown mounted on platforml2. Also mounted on platform I2 is upright supporting member i3. Pulleywheel I 5 is attached to. one end of a shaft (notshown) which isrotatably positioned in a transverse housing provided in the upperportion of support I3; cutting disc i6 is attached to the other end ofthe shaft. Disc I6 is of relatively thin metal, for example it may be ofNo. 16 to No. 20 gauge steel or copper, and is preferably provided withtwo reinforcing flanges, one of these flanges I! being shown and thesecond, which is similar to flange I1 and mounted on the opposite faceof disc 16, not being shown.

A tank 2| is supported from upright member I3 by bracket members 22 and23; this tank serves as a container for the abrasiveliquid, preferablykerosene carrying abrasive particles. Also supported from upright memberI3, by means of a third bracket member ,is table 25 which serves as asupport for the material being out.

A portion 3| of hard material, such as quartz or. glass, is held againstthe blade'in position where it is also cut during cutting of thematerial supported on table 25. This material may be held in position byhand or, if desired, a suitable work-holding table, similar to table 25,may be provided for the purpose.

In order to further describe the arrangement, let us assume that a slabis to be sawed from Rochelle salt crystal 32 which is shown in posicatedby the arrow. This motion is, of course, transmitted to disc It by theconnecting shaft so that disc I6 now rotates in the same direction aspulley l5; the rate at which disc I6 is rotated should preferably berelatively slow, for example, in the neighborhood of 150 revolutions perminute.

Tank 2| is filled with the abrasive mixture, preferably kerosenecarrying abrasive particles, to a sufiicient level to insure that asubstantial portion of disc 16 is submerged in the liquid at all times.As the disc rotates, portions of the abrasive cling to the edge of thedisc and are carried around to the sawing point where they are effectivein furthering the cutting effect of the thin hard edge of disc 16. Theuse of kerosene rather than liquids used heretofore, particularly water,has proven advantageous as evaporation is avoided; evaporation isobjectionable as the resulting cooling of the Rochelle salt causesexcessive breakage of the fragile material.

Further, the Rochelle salt is not dissolved or otherwise afiecteddeieteriously by the kerosene.

It has previously been observed by applicant that, when saws of thisgeneral nature have been used for cutting Rochelle salt, a saltyaccumulation tends to become glazed on the cutting edge of thedisc andthat the rate of cutting is reduced thereby to an unsatisfactory degree.In the instance of the saw of the present invention, however, engagementof the edge of disc IS with the extremely hard material 3| is effectiveto break away this brittle glazed coating before it can build upsufiiciently to be at all objectionable. While engagement of material 3|with the edge of disc I6 tends to break away the brittle accumulation ofsalt, it tends, on the contrary, to force the abrasive particles carriedby the disc into somewhat more intimate contact with the disc materialthan would be achieved in the absence of material 3|.

While material 3i is, of course, cut by disc 16 this cutting is at avery low rate compared to the rate at which the much softer material 32is cut; when a cut of considerable depth has been made in block 31, itsposition may be changed to start a new out and after several cuts havebeen made the block may be discarded and a fresh block provided.

While a specific embodiment of the invention has been selected fordetailed description, the invention is not, of course, so limited in itsapplication. The embodiment described should be taken as illustrative ofthe invention and not as restrictive thereof.

What is claimed is:

l. The method of cutting Rochelle salt by means of a rotatable discpassing through a liquid containing an abrasive which includes the stepof holding a portion of quartz against the cutting edge of the disc inorder to remove accumulated Rochelle salt therefrom,

2. The method of cutting relatively thin slabs from a bod of Rochellesalt by means of a relatively thin rotatable disc passing through aliquid containing an abrasive which includes the step of simultaneouslycutting with said disc a relatively thin slot in a body of quartz.

JAMES J. GILLICH.

